Continuity mistake: Charlie, Olivia's former partner and friend in the FBI shows up in this episode during the interview with Mrs. Rusk, but Charlie was killed off by one of the shapeshifters in a previous episode, and the shapeshifter that killed Charlie was himself killed off by Olivia, who in other episodes reflected back on killing him. This episode was supposedly meant to be in season 1 as ep 21 or 22. Unknown why they didn't air it then, and decided to put it in the middle of season 2 (for no apparent reason).
Cold Ground - S1-E6
Continuity mistake: When Sookie is eating Adele's pie, the amount of pie on the fork keeps changing between shots. (00:41:25)
Continuity mistake: Whenever the Big Brother eye is shown, it is grey and white. But there is a shot of a woman leaving the house in the first episode in which you can see the eye from Big Brother 9 (which is shattered with one red shard) on a platform at the bottom of the stairs.
Containment - S1-E5
Continuity mistake: At the end of the episode, when the bad guy is preparing the syringe of small pox, he follows the usual method of tapping out any air in the tube - when he is shown injecting himself, a large air bubble is back in the syringe (which would probably kill him quicker than the smallpox).